Actually, I really think the idea that ties The End of Eternity into the Foundation series is incredibly brilliant.

That being said, I strongly believe that either can be read independently of the other. In particular, there is nothing in Foundation that depends in any significant way on The End of Eternity. It's just a detail that may not occur to the reader on even the second reading of Foundation. But it's still really neat.

I also strongly believe that the books can, and probably should, be read in the order in which they were published.

__________________“A life is like a garden. Perfect moments can be had, but not preserved, except in memory. LLAP” — Leonard Nimoy (1931-2015)